Streaming QoE engagement calculator

A dependency-free (pure standard-library) Python tool that turns the streaming QoE metrics this article frames into an estimated engagement impact, using the published causal/empirical models so the output traces to a citable source. It does NOT decode video or compute picture metrics; it consumes the session-level numbers a player analytics stack already reports. (1) STARTUP -> ABANDONMENT: applies the Krishnan-Sitaraman (IMC 2012) finding — abandonment begins past ~2s and rises ~5.8 percentage